Carboxamide substituted tetramethylcyclopentadiene – synthesis, characterisation and its iridium( iii ) complex catalysed reduction of imines. Mwansa, J. M., Stirling, M. J., Sweeney, G., Hanusek, J., Váňa, J., & Page, M. I. Dalton Transactions, 2022.
doi  abstract   bibtex   
The novel dimeric iodo-iridium( iii ) complex bearing an amide moiety within the tetramethylcyclopentadiene ring, has been synthesised, characterised and its catalytic activity has been evaluated in the transfer hydrogenation of imines. The novel dimeric iodo-iridium( iii ) complex, [Ir(Cp*CONMe 2 )I 2 ] 2 , (Cp*CONMe 2 = η 5 - N,N -2,3,4,5-hexamethylcyclopenta-2,4-diene carboxamide) bearing an amide moiety within the tetramethylcyclopentadiene ring, has been synthesised and characterised. The ligand Cp*CONMe 2 is synthesised as two regioisomers, however the 2-substituted isomer exists as two distinguishable conformers due to restricted rotation about the amide carbonyl carbon and the ring carbon. The relative acidities of Cp*CONMe 2 and Cp* are compared by their relative rates of H/D exchange. The iridium complex of N,N -2,3,4,5-hexamethylcyclopenta-2-4-diene carboxamide [IrCp*CONMe 2 ] and ( R,R )-1,2-diphenyl- N ′-tosylethane-1,2-diamine (( R , R )-TsDPEN) has been evaluated in the transfer hydrogenation of imines under acidic conditions – a 5 : 2 molar ratio of formic acid : triethylamine as the hydride source for the transfer hydrogenation of 1-methyl-3,4-dihydroisoquinoline (DHIQ) and its 6,7-dimethoxy derivative in acetonitrile. A decreasing enantiomeric excess with reaction progress is attributed to different kinetic orders for formation of the two product amine enantiomers. The pseudo zero-order formation of the R -amine may be due to a pre-steady-state formation of the less stable form of the diastereomeric catalyst. By contrast, both enantiomeric amines from 1-fluorinated methyl DHIQs as substrates for reduction are formed by pseudo first-order processes.
@article{mwansa_carboxamide_2022,
	title = {Carboxamide substituted tetramethylcyclopentadiene – synthesis, characterisation and its iridium( iii ) complex catalysed reduction of imines},
	issn = {1477-9226},
	doi = {10.1039/d2dt00149g},
	abstract = {The novel dimeric iodo-iridium( iii ) complex bearing an amide moiety within the tetramethylcyclopentadiene ring, has been synthesised, characterised and its catalytic activity has been evaluated in the transfer hydrogenation of imines. The novel dimeric iodo-iridium( iii ) complex, [Ir(Cp*CONMe 2 )I 2 ] 2 , (Cp*CONMe 2 = η 5 - N,N -2,3,4,5-hexamethylcyclopenta-2,4-diene carboxamide) bearing an amide moiety within the tetramethylcyclopentadiene ring, has been synthesised and characterised. The ligand Cp*CONMe 2 is synthesised as two regioisomers, however the 2-substituted isomer exists as two distinguishable conformers due to restricted rotation about the amide carbonyl carbon and the ring carbon. The relative acidities of Cp*CONMe 2 and Cp* are compared by their relative rates of H/D exchange. The iridium complex of N,N -2,3,4,5-hexamethylcyclopenta-2-4-diene carboxamide [IrCp*CONMe 2 ] and ( R,R )-1,2-diphenyl- N ′-tosylethane-1,2-diamine (( R , R )-TsDPEN) has been evaluated in the transfer hydrogenation of imines under acidic conditions – a 5 : 2 molar ratio of formic acid : triethylamine as the hydride source for the transfer hydrogenation of 1-methyl-3,4-dihydroisoquinoline (DHIQ) and its 6,7-dimethoxy derivative in acetonitrile. A decreasing enantiomeric excess with reaction progress is attributed to different kinetic orders for formation of the two product amine enantiomers. The pseudo zero-order formation of the R -amine may be due to a pre-steady-state formation of the less stable form of the diastereomeric catalyst. By contrast, both enantiomeric amines from 1-fluorinated methyl DHIQs as substrates for reduction are formed by pseudo first-order processes.},
	journal = {Dalton Transactions},
	author = {Mwansa, Joseph M. and Stirling, Matthew J. and Sweeney, Gemma and Hanusek, Jiří and Váňa, Jiří and Page, Michael I.},
	year = {2022},
}

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